(Mar 9, 2019, 10:20 AM)Gentleman Wrote: Dear @champninjastar,
nice to meet you. Please for your questions in the future try to set up your Pokemon in your query in a clearer way, like 1.) Garchomp ... until the last one with 6.) Kartana. This makes it much easier to keep a good overview. Thank you. Anyway, I can help you with your team. Lets's break this down.
1.) Garchomp @ Garchompite 
Ability: Rough Skin 
EVs: 6 HP / 252 Atk / 252 Spe 
Jolly Nature 
- Dragon Claw 
- Rock Slide 
- Swords Dance 
- EarthquakeJ
Please take care, when megaevolving Garchomp you lose ten stat points on speed. Therefore, I would rather play Garchomp with Jolly nature and 252 EV on speed to compensate this. Especially since you already have enough power because of mega stone and Swords Dance.

2.) Clefable @ Leftovers 
Ability: Magic Guard 
EVs: 252 HP / 252 Def / 4 SpD 
Bold Nature 
IVs: 0 Atk 
- Stealth Rock 
- Moonblast 
- Flamethrower
- Soft-Boiled
I would go for Flamethrower instead of Whish since you are already able to heal yourself with Soft-boiled. 

3.) Magearna @ Assault Vest 
Ability: Soul-Heart 
EVs: 252 HP / 252 SpD / 4 Spe 
Sassy Nature 
- Fleur Cannon 
- Iron Head 
- Volt Switch 
- Ice Beam
Since your Clefable already covers the fire type with Flamethrower I would choose Ice Beam instead of Hidden Power.

4.) Excadrill @ Focus Sash 
Ability: Mold Breaker 
EVs: 6 HP / 252 Atk / 252 Spe 
Jolly Nature 
- Rapid Spin 
- Earthquake 
- Toxic
- Protect / Horn Drill / X-Scissor
I recommend to go fully offensive with this Pokemon. Therefore, Jolly nature and max EV on speed since speed base stats are not the best. Furthermore, maybe you consider using Horn Drill or X-Scissor instead of Protect.

5.) Mimikyu @ Mimikium Z 
Ability: Disguise 
EVs: 252 Atk / 4 SpD / 252 Spe 
Jolly Nature 
- Swords Dance 
- Play Rough 
- Shadow Sneak 
- Drain Punch
Again Jolly nature since you already have enough power with Swords Dance.

6.) Kartana @ Grassium Z 
Ability: Beast Boost 
EVs: 252 Atk / 4 SpD / 252 Spe 
Adamant Nature 
- Leaf Blade 
- Sacred Sword 
- Smart Strike 
- X-Scissor / Aerial Ace
Aerial Ace would also be an option to have a look at.

Overall interesting team. However, please consider two things.
- You have Steel type and Fairy type each 3 times in your team.
- You don't have a special offensive Pokemon like a special sweeper in your team. 
  Only physical offensive ones; Garchomp, Excadrill, Mimikyu and Kartana.
Therefore, maybe you think of substituting one or more of your Pokemon for other choices.

Hopefully I was able to help you. Have a good one.
Best,
Gernot